A Bangladesh tribunal has sentenced an Islamic cleric formerly tied to a fundamentalist party to death for crimes against humanity for his actions during the country's 1971 independence war.

The conviction of Abul Kalam Azad was the first verdict handed down by the controversial tribunal trying people accused of committing crimes during the war.

Azad, a former senior member of the Jamaat-e-Islami party, was tried in his absence after he reportedly fled to Pakistan last April upon being charged. He was expelled from the party.

Jamaat-e-Islami campaigned in 1971 against Bangladesh's war of separation from Pakistan. The party stands accused of supporting or in some cases taking part in atrocities committed by Pakistani troops.

The government has appointed a defence counsel for Azad, widely known for his regular appearances on a television channel and for his coloured beard, but the counsel said he did not get support from his family to present witnesses against the prosecution charges.

Azad's two sons and a son-in-law were arrested last year after he reportedly fled the country. They told reporters that Azad fled the country hours before security officials raided his home in Dhaka.

Bangladesh says that during the nine-month war, Pakistani troops, aided by their local collaborators, killed three million people and raped about 200,000 women.

International human rights groups have raised questions about the conduct of the tribunals set up by the government to prosecute those accused of war crimes.

The courtroom was packed as Obaidul Hassan, the head judge of a separate, three-member tribunal, pronounced Azad guilty of crimes including murder, abduction and looting.

Judge Hassan said Azad was "guilty of crimes against humanity beyond a reasonable doubt".